Bidestillatus
The term Bidestillatus is a common Latin term in chemistry and medicine for double distilled (abbreviation: Bidest. Or dd ).
A vaporizable substance of particularly high purity is obtained by double distillation. The fraction that has already been rectified is poured again into the distillation flask to remove any remaining impurities.
A double distillation is carried out on substances to which an extraordinary degree of purity is required, e.g. As water for injection after the European Pharmacopoeia . This germ-free, extremely low-salt water is used, among other things, to make eye drops .